diff --git a/src/ecmascript/mujs.c b/src/ecmascript/mujs.c
index 715d33a3e..952416baa 100644
--- a/src/ecmascript/mujs.c
+++ b/src/ecmascript/mujs.c
@@ -26,6 +26,7 @@
 #include "ecmascript/ecmascript.h"
 #include "ecmascript/mujs.h"
 #include "ecmascript/mujs/console.h"
+#include "ecmascript/mujs/customevent.h"
 #include "ecmascript/mujs/document.h"
 #include "ecmascript/mujs/element.h"
 #include "ecmascript/mujs/event.h"
@@ -141,6 +142,7 @@ mujs_get_interpreter(struct ecmascript_interpreter *interpreter)
 	mjs_event_init(J);
 	mjs_keyboardEvent_init(J);
 	mjs_messageEvent_init(J);
+	mjs_customEvent_init(J);
 
 	return J;
 #if 0
diff --git a/src/ecmascript/mujs/Makefile b/src/ecmascript/mujs/Makefile
index 97b005fbd..cb2566d8b 100644
--- a/src/ecmascript/mujs/Makefile
+++ b/src/ecmascript/mujs/Makefile
@@ -1,7 +1,7 @@
 top_builddir=../../..
 include $(top_builddir)/Makefile.config
 
-OBJS = attr.o attributes.o collection.o console.o css.o document.o element.o event.o form.o forms.o history.o implementation.o input.o \
+OBJS = attr.o attributes.o collection.o console.o css.o customevent.o document.o element.o event.o form.o forms.o history.o implementation.o input.o \
 	keyboard.o localstorage.o location.o mapa.o message.o navigator.o nodelist.o screen.o style.o unibar.o window.o xhr.o
 
 include $(top_srcdir)/Makefile.lib
diff --git a/src/ecmascript/mujs/customevent.c b/src/ecmascript/mujs/customevent.c
new file mode 100644
index 000000000..1e2450ff4
--- /dev/null
+++ b/src/ecmascript/mujs/customevent.c
@@ -0,0 +1,238 @@
+/* The MuJS CustomEvent object implementation. */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "elinks.h"
+
+#include "ecmascript/ecmascript.h"
+#include "ecmascript/mujs.h"
+#include "ecmascript/mujs/customevent.h"
+#include "intl/charsets.h"
+#include "terminal/event.h"
+
+static void mjs_customEvent_get_property_bubbles(js_State *J);
+static void mjs_customEvent_get_property_cancelable(js_State *J);
+static void mjs_customEvent_get_property_composed(js_State *J);
+static void mjs_customEvent_get_property_defaultPrevented(js_State *J);
+static void mjs_customEvent_get_property_detail(js_State *J);
+static void mjs_customEvent_get_property_type(js_State *J);
+
+static void mjs_customEvent_preventDefault(js_State *J);
+
+struct eljscustom_event {
+	const char *detail;
+	char *type_;
+	unsigned int bubbles:1;
+	unsigned int cancelable:1;
+	unsigned int composed:1;
+	unsigned int defaultPrevented:1;
+};
+
+static void
+mjs_customEvent_finalizer(js_State *J, void *val)
+{
+	struct eljscustom_event *event = (struct eljscustom_event *)val;
+
+	if (event) {
+		if (event->detail) {
+			js_unref(J, event->detail);
+		}
+		mem_free_if(event->type_);
+		mem_free(event);
+	}
+}
+
+void
+mjs_push_customEvent(js_State *J, char *type_)
+{
+	struct eljscustom_event *event = (struct eljscustom_event *)mem_calloc(1, sizeof(*event));
+
+	if (!event) {
+		js_error(J, "out of memory");
+		return;
+	}
+	event->type_ = null_or_stracpy(type_);
+
+	js_newobject(J);
+	{
+		js_newuserdata(J, "event", event, mjs_customEvent_finalizer);
+		addmethod(J, "preventDefault", mjs_customEvent_preventDefault, 0);
+		addproperty(J, "bubbles", mjs_customEvent_get_property_bubbles, NULL);
+		addproperty(J, "cancelable", mjs_customEvent_get_property_cancelable, NULL);
+		addproperty(J, "composed", mjs_customEvent_get_property_composed, NULL);
+		addproperty(J, "defaultPrevented", mjs_customEvent_get_property_defaultPrevented, NULL);
+		addproperty(J, "detail", mjs_customEvent_get_property_detail, NULL);
+		addproperty(J, "type", mjs_customEvent_get_property_type, NULL);
+	}
+}
+
+static void
+mjs_customEvent_get_property_bubbles(js_State *J)
+{
+#ifdef ECMASCRIPT_DEBUG
+	fprintf(stderr, "%s:%s\n", __FILE__, __FUNCTION__);
+#endif
+	struct eljscustom_event *event = (struct eljscustom_event *)js_touserdata(J, 0, "event");
+
+	if (!event) {
+		js_pushnull(J);
+		return;
+	}
+	js_pushboolean(J, event->bubbles);
+}
+
+static void
+mjs_customEvent_get_property_cancelable(js_State *J)
+{
+#ifdef ECMASCRIPT_DEBUG
+	fprintf(stderr, "%s:%s\n", __FILE__, __FUNCTION__);
+#endif
+	struct eljscustom_event *event = (struct eljscustom_event *)js_touserdata(J, 0, "event");
+
+	if (!event) {
+		js_pushnull(J);
+		return;
+	}
+	js_pushboolean(J, event->cancelable);
+}
+
+static void
+mjs_customEvent_get_property_composed(js_State *J)
+{
+#ifdef ECMASCRIPT_DEBUG
+	fprintf(stderr, "%s:%s\n", __FILE__, __FUNCTION__);
+#endif
+	struct eljscustom_event *event = (struct eljscustom_event *)js_touserdata(J, 0, "event");
+
+	if (!event) {
+		js_pushnull(J);
+		return;
+	}
+	js_pushboolean(J, event->composed);
+}
+
+static void
+mjs_customEvent_get_property_defaultPrevented(js_State *J)
+{
+#ifdef ECMASCRIPT_DEBUG
+	fprintf(stderr, "%s:%s\n", __FILE__, __FUNCTION__);
+#endif
+	struct eljscustom_event *event = (struct eljscustom_event *)js_touserdata(J, 0, "event");
+
+	if (!event) {
+		js_pushnull(J);
+		return;
+	}
+	js_pushboolean(J, event->defaultPrevented);
+}
+
+static void
+mjs_customEvent_get_property_detail(js_State *J)
+{
+#ifdef ECMASCRIPT_DEBUG
+	fprintf(stderr, "%s:%s\n", __FILE__, __FUNCTION__);
+#endif
+	struct eljscustom_event *event = (struct eljscustom_event *)js_touserdata(J, 0, "event");
+
+	if (!event || !event->detail) {
+		js_pushnull(J);
+		return;
+	}
+	js_getregistry(J, event->detail);
+}
+
+static void
+mjs_customEvent_get_property_type(js_State *J)
+{
+#ifdef ECMASCRIPT_DEBUG
+	fprintf(stderr, "%s:%s\n", __FILE__, __FUNCTION__);
+#endif
+	struct eljscustom_event *event = (struct eljscustom_event *)js_touserdata(J, 0, "event");
+
+	if (!event) {
+		js_pushnull(J);
+		return;
+	}
+	js_pushstring(J, event->type_ ?: "");
+}
+
+static void
+mjs_customEvent_preventDefault(js_State *J)
+{
+#ifdef ECMASCRIPT_DEBUG
+	fprintf(stderr, "%s:%s\n", __FILE__, __FUNCTION__);
+#endif
+	struct eljscustom_event *event = (struct eljscustom_event *)js_touserdata(J, 0, "event");
+
+	if (!event) {
+		js_pushnull(J);
+		return;
+	}
+	if (event->cancelable) {
+		event->defaultPrevented = 1;
+	}
+	js_pushundefined(J);
+}
+
+static void
+mjs_customEvent_fun(js_State *J)
+{
+#ifdef ECMASCRIPT_DEBUG
+	fprintf(stderr, "%s:%s\n", __FILE__, __FUNCTION__);
+#endif
+	js_pushundefined(J);
+}
+
+static void
+mjs_customEvent_constructor(js_State *J)
+{
+#ifdef ECMASCRIPT_DEBUG
+	fprintf(stderr, "%s:%s\n", __FILE__, __FUNCTION__);
+#endif
+	struct eljscustom_event *event = (struct eljscustom_event *)mem_calloc(1, sizeof(*event));
+
+	if (!event) {
+		return;
+	}
+	event->type_ = null_or_stracpy(js_tostring(J, 1));
+
+	js_getproperty(J, 2, "bubbles");
+	event->bubbles = js_toboolean(J, -1);
+	js_pop(J, 1);
+	js_getproperty(J, 2, "cancelable");
+	event->cancelable = js_toboolean(J, -1);
+	js_pop(J, 1);
+	js_getproperty(J, 2, "composed");
+	event->composed = js_toboolean(J, -1);
+	js_pop(J, 1);
+	if (js_hasproperty(J, 2, "detail")) {
+		event->detail = js_ref(J);
+	}
+
+	js_newobject(J);
+	{
+		js_newuserdata(J, "event", event, mjs_customEvent_finalizer);
+		addmethod(J, "preventDefault", mjs_customEvent_preventDefault, 0);
+		addproperty(J, "bubbles", mjs_customEvent_get_property_bubbles, NULL);
+		addproperty(J, "cancelable", mjs_customEvent_get_property_cancelable, NULL);
+		addproperty(J, "composed", mjs_customEvent_get_property_composed, NULL);
+		addproperty(J, "defaultPrevented", mjs_customEvent_get_property_defaultPrevented, NULL);
+		addproperty(J, "detail", mjs_customEvent_get_property_detail, NULL);
+		addproperty(J, "type", mjs_customEvent_get_property_type, NULL);
+	}
+}
+
+int
+mjs_customEvent_init(js_State *J)
+{
+	js_pushglobal(J);
+	js_newcconstructor(J, mjs_customEvent_fun, mjs_customEvent_constructor, "CustomEvent", 0);
+	js_defglobal(J, "CustomEvent", JS_DONTENUM);
+	return 0;
+}
diff --git a/src/ecmascript/mujs/customevent.h b/src/ecmascript/mujs/customevent.h
new file mode 100644
index 000000000..38640f50a
--- /dev/null
+++ b/src/ecmascript/mujs/customevent.h
@@ -0,0 +1,16 @@
+#ifndef EL__ECMASCRIPT_MUJS_CUSTOMEVENT_H
+#define EL__ECMASCRIPT_MUJS_CUSTOMEVENT_H
+
+#include <mujs.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+int mjs_customEvent_init(js_State *J);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
diff --git a/src/ecmascript/mujs/meson.build b/src/ecmascript/mujs/meson.build
index 10a345d38..e758c52f1 100644
--- a/src/ecmascript/mujs/meson.build
+++ b/src/ecmascript/mujs/meson.build
@@ -1,2 +1,2 @@
-srcs += files('attr.c', 'attributes.c', 'collection.c', 'console.c', 'css.c', 'document.c', 'element.c', 'event.c', 'form.c', 'forms.c', 'history.c', 'implementation.c', 'input.c', 'keyboard.c',
+srcs += files('attr.c', 'attributes.c', 'collection.c', 'console.c', 'css.c', 'customevent.c', 'document.c', 'element.c', 'event.c', 'form.c', 'forms.c', 'history.c', 'implementation.c', 'input.c', 'keyboard.c',
 'localstorage.c', 'location.c', 'mapa.c', 'message.c', 'navigator.c', 'nodelist.c', 'screen.c', 'style.c', 'unibar.c', 'window.c', 'xhr.c')